Nodal Metastasis

Lymph node metastases are common in pancreatic tumors because of rich lymphatic networks around the pancreas. They are found in 40-75% of patients with tumors larger than 2 cm on pathologic examinations.4 The majority of lymph node metastases are found at the peripancreatic nodal group, including the anterior and posterior peripancreatic nodes, pancreaticoduodenal lymph nodes, pyloric nodes (Fig. 12-13), and inferior

Pancreatico Duodenal Lymph Nodes

Fig. 12—12. Ductal adenocarcinoma of head of pancreas.

Tumor (T) involves the superior mesenteric vein (large arrow), a type D involvement. Tumor was resected with venous resection. The small hypodense nodule (small arrow) between the SMV and SMA was confirmed to be a metastatic node.

Pancreaticoduodenal Lymph Node

Fig. 12—13. Pancreatic ductal adenocarcinoma involving body and cephalad portion of head of pancreas.

Note node (n) anterior to the gastroduodenal artery (arrow) and behind the gastric antrum (St). A metastatic node was confirmed at surgery. T = tumor in body of pancreas.

Fig. 12—13. Pancreatic ductal adenocarcinoma involving body and cephalad portion of head of pancreas.

Note node (n) anterior to the gastroduodenal artery (arrow) and behind the gastric antrum (St). A metastatic node was confirmed at surgery. T = tumor in body of pancreas.

nodes along the IPDA (Fig. 12-14). Metastases to the nodes in the hepatoduodenal ligament, common hepatic nodes, and celiac node are rare (less than 10%).4 Currently, preoperative assessment of nodal metastasis by CT or MR is not accurate enough to make an impact on surgical planning because no better criteria of nodal metastasis can be applied other than the size.20-22 MR may provide a better potential because metastatic nodes may be hyperintense on T2-weighted images, but this potential has yet to be proved. The Radiology Diagnostic Oncology Group study has shown that the sensitivity to predict nodal metastasis was only 37% by CT and 34% by MR, and the specificity was 60% by CT and 76% by MR, with the positive and negative predictive values ranging between 47% and 57%.21 The results from our unpublished data using the thin-section CT scanning technique are similar to this study. We believe that these poor results are due to several factors, including (a) the inability to diagnose microscopic metastasis in small nodes (3-5 mm); (b) the large inflammatory nodes mistaken as metastasis; (c) poor understanding of the pathways of nodal metastasis in pancreatic tumors in cross-sectional imaging; and (d) possibly misinterpreting tumor infiltration as a nonnodal disease. It should be emphasized that nodal metastasis around the pancreas would not impact surgical planning because metastatic nodes are mostly removed in the specimen of pancre-aticoduodenectomy; however, its presence would influ

Fig. 12-14. Large tumor (T) involving head of pancreas.

Multiple hypodense nodes are shown along the SMA and jejunal mesentery (short arrows) and the upper paraaortic region (long arrow). This is the descending or inferior pathway of nodal metastasis.

Fig. 12-14. Large tumor (T) involving head of pancreas.

Multiple hypodense nodes are shown along the SMA and jejunal mesentery (short arrows) and the upper paraaortic region (long arrow). This is the descending or inferior pathway of nodal metastasis.

Metastasis Pathway

ence the outcome of surgery. It is more important to recognize nodal metastasis in the nodal groups, such as the mesenteric nodes, the common hepatic artery node, and the celiac node, that may not be included in the resected specimen because metastasis to these nodes would preclude patients from surgery.

Recently, we developed new criteria to try to improve the sensitivity and specificity in predicting nodal metastasis in patients with pancreatic carcinoma.23 We have observed that (a) low-density nodes with irregular margins are highly specific for metastatic disease but they are not sensitive enough to detect the majority of meta-static nodes (Figs. 12-12 and 12-14); (b) using the size of lymph node larger than 5 mm in the inferior pancreatic nodal group increases the sensitivity to detect nodal metastasis; and (c) enlarged nodes in the periportal and common hepatic nodal groups are nonspecific and can be seen in patients with chronic pancreatitis or node-negative pancreatic cancer.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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